Monday, March 16, 2020

String Concatenation in Python Language



As we all now the Python language is one of the most powerful languages of the present time. As in the previous languages, we have char data type as the primitive data type but this is something different in the Python language. This means that Python does not have a data type corresponding to the character. In Python language, strings have type str. String in Python language represents the sequence of characters. In Python language, the strings are immutable which means that once created they cannot be changed or modified. This means when we want to modify the string it can not be done in the existing string a new string required to be created.
The word concatenation means to join some objects together. In Python language, the following methods are used to join two or more string together:-
  1. + operator
  2. Using join() method
  3. % operator
  4. Using format() function
  5. Using f-string (Interpolation of literal string)
Concatenation using + operator
In Python Language, the + operator is used to merge two or more string. for example, suppose we have two strings as follows
a="This is "
b="Power of Python"
c=a+b
print(c)
Considering the above program we have a string store in which is "This is " and b store "Power of Python" then we have concatenated the two string into the third-string called c. So when we print the value of variable c then it will print "This is Power of Python". Similarly, we can add more than two string together. for example
a="First "
b="Second "
c="Third "
d="Fourth"
e=a+b+c+d
print(e)
The output string will be "First Second Third Fourth".
The point here to be noted that we can not append the value of the same string. for example, suppose we have the following code:
a="First"
b=7
c=a+b
print(c)
This code will generate the following error
File "C:/Users/DELL/.spyder-py3/temp.py", line 9, in <module>
    c=a+b
TypeError: can only concatenate str (not "int") to str
from this error, we came to know + operator only works when both values are str only.
Concatenation using join() method
The string concatenation, when done by + operator, doesn't provide any option to print any delimiter. So if we want to print the string with separator we can do it using join() method. for example
s1="This"
s2="Python"
s3="Language"
s4=" ".join([s1,s2,s3])
print(s4)
The above course will give the following output
This Python Language
if we do not want any delimiter then we can use empty string before the join() method. for example
s1="This"
s2="Python"
s3="Language"
s4="".join([s1,s2,s3])
print(s4)
The output of this code is
ThisPythonLanguage
We can also put any character to separate each string with others. for example
s1="This"
s2="Python"
s3="Language"
s4=", ".join([s1,s2,s3])
print(s4)
Output
The above code will give output as This, Python, Language
Concatenation using % operator
Another way by which we can perform the concatenation of two or more strings is by using the % operator. Like in C language the % sign is called the format specifier. So we can use %s to determine the string, %d can use to specify integer, etc. Consider the following code:
s1="This"
s2="Python"
s3="Language"
s4="%s %s %s " % (s1,s2,s3)
print(s4)
The output of this code will be 
This Python Language
To analyze the above code there are three strings s1,s2, and s3. These strings are represented by individual %s symbol and by % operator get concatenated into the fourth string s4. Now take another example:
s1="The"
s2="sum"
s3="of"
a=int(input("Enter the first Number"))
b=int(input("Enter the Second Number"))
c=a+b
s4="%s %s %s %d and %d is %d " % (s1,s2,s3,a,b,c)
print(s4)
The output of this code will yield the following:
Enter the first Number10
Enter the Second Number70
The sum of 10 and 70 is 80
Concatenation of strings using the format() method
The format() function used with strings is a very a versatile and powerful function used for formatting strings. Using this method for concatenation is the utilization of just one feature of format() method. The format strings method has curly braces { } as the placeholders or replacement arguments or fields which get replaced. Here we can use positional arguments or keyword arguments to specify the order of the fields that have to be replaced. Consider the following code
s1="{},{} and {}".format('One','Two','Three')
print("Default sequence of argument is :",s1)
s2="{1},{0} and {2}".format('One','Two','Three')
print("Positional Sequence of argument is : ",s2)
The output of this code will be
Default sequence of argument is: One, Two and Three
Positional Sequence of argument is: Two, One and Three
So we can see that in string s1 we store the list of three arguments "One, Two and Three" which become the default sequence and in the second string s2 we have passed the positional sequence.
It is very unfair to use the format() method only for the string concatenation but it is one of the methods which can be used for this purpose also.
Using f-string (Interpolation of literal string)
The f-string methods can only be used if we are using Python 3.6 onwards. Consider the following code where the f-string method is used for the concatenation purpose.
s1="Python"
s2="Language"
s3="is"
s4="Powerful"
s5=f'{s1} {s2} {s3} {s4}'
print(s5)
The output of the above code will be as follows
Python Language is Powerful
The value of s1, s2, s3, and s4 gets stored in s5.
So to conclude we can use string concatenation in python in several ways. We have to use different methods depending upon the requirement or our needs in the program. Suppose if we want to concatenate the strings using delimiter we can use join() method. If we know the usage of % we can use it for the concatenation method. We can use format() method also but the format() method can be used for more things than simply for concatenation. If we are using the updated version of python we can use the f-string method which more decent to use when compared to format() method. In my opinion for simple concatenation of strings, we should use the + operator which is very easy among all other options available.




List Comprehension In Python Language


List Comprehension

In Python Language, the list is the most versatile data type. A list consists of different items or data separated by commas and enclosed between square brackets ([]). The list in Python is similar to the arrays in C,
C++ and Java programming. The main difference between the arrays and the list is that array is the collection of the same type of data types wherein the list we can have different types of data. Now suppose we want to create the empty list we can use the following syntax:
l=[]
print(type(l))
We can also create an empty list by using the built-in list type objects. For example, we can create the list by using the following code:
l=list()
The Python Language also supports the computed lists called list comprehensions. We can also be called the list comprehension is a concise way of creating the list. This is similar to Math's set builder notation. Suppose we have to represent the set of squares of natural numbers from 1 to 10 then we can use the following methods.
square=[]
for i in range(1,11):
    square.append(i**2)
print("The square of numbers from 1 to 10 is", square)
The output of the above code result in:
The square of numbers from 1 to 10 is [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
The same can be written as follows:
square=[(x*x) for x in range(1,11)]
print(square)
 The output of the above code is
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
The syntax for creating the list comprehension is as follows:
list=[ expression for variable in sequence ]
Where the expression is evaluated once, for every item in the sequence.
So in every list comprehension, we have the following parts:
  1. the expression is the member itself which is used to call a valid expression that can return some values. In the above example (x*x) is the expression.
  2. member is the value whose lies between the sequence provided in the list.
  3. iterable is a list, sequence or any other item that can return the single value at a time.
So with the help of List comprehension, we can create very easily the lists consists of many items. List comprehension helps programmers or coders to create the lists concisely. This is mainly beneficial to make new lists where each element is obtained by applying some operations to each member of another sequence or iterable. We should note that an iterable is the object that can be used repeatedly in subsequent loop statements. let us take another example of list comprehensions. As we know the list comprehension consists of a square bracket containing an expression followed by a for clause, then zero or more for or if clauses. Suppose we have the following list numbers:
numbers=[-1, 2, 34, -9, -10, 7, 8, 9, 121, 0]
And now if we want to get all positive numbers in the list then we can use the following code:
numbers=[-1,2,34,-9,-10,7,8,9,121,0]
p=[x for x in numbers if x>=0]
print(p)
The output of the above code will be as follows:
[2, 34, 7, 8, 9, 121, 0]
So from the above code, we can deduce that here x is bound with every value in the list numbers that are -1, 2, 34, -9, -10, 7, 8, 9, 121 and 0. But the if clause will filter only value where the condition x>=0 is true i.e. 2, 34, 7, 8, 9, 121 and 0. 
Now let us take another example if we want to print all the vowels in the given sentence we can use list comprehension in the following ways:
sentence="This is the sentence which is used to check the power of the list comprehension"
vo=[x for x in sentence if x in 'aeiou']
print(vo)
The output of this code will be as follow:
['i', 'i', 'e', 'e', 'e', 'e', 'i', 'i', 'u', 'e', 'o', 'e', 'e', 'o', 'e', 'o', 'e', 'i', 'o', 'e', 'e', 'i', 'o']
And suppose we have to do vice-versa the following code will work:
sentence="This is the sentence which is used to check the power of the list comprehension"
co=[x for x in sentence if x not in 'aeiou']
print(co)
The output will be:
['T', 'h', 's', ' ', 's', ' ', 't', 'h', ' ', 's', 'n', 't', 'n', 'c', ' ', 'w', 'h', 'c', 'h', ' ', 's', ' ', 's', 'd', ' ', 't', ' ', 'c', 'h', 'c', 'k', ' ', 't', 'h', ' ', 'p', 'w', 'r', ' ', 'f', ' ', 't', 'h', ' ', 'l', 's', 't', ' ', 'c', 'm', 'p', 'r', 'h', 'n', 's', 'n']
We can also use the list comprehensions to combines the elements of two list. Consider the following code:
print([(x,y) for x in [10,20,30] for y in [30, 40, 10] if x!=y])
The output of the code will be 
[(10, 30), (10, 40), (20, 30), (20, 40), (20, 10), (30, 40), (30, 10)]
In the code, two values, one from each list is used to create a new list only if the two values are not same.
Now with all the above examples, we come to the conclusion that Python language had provided a strong tool for a list comprehension. This can be easily used to deduce the long codes into the smaller and easily understandable codes. As lists are mutable so they can be easily appended and list comprehension is one of the methods to create the long list where the data or item is generated with the help of the following two ways:
  • expression
  • filters
The filters can be easily combined to get the desired list as we have done in extracting the vowels or constants.
We not only create list comprehensions but we can also create the dictionary comprehensions the only difference is that we require the key-value pair in it. So to utilize the complete power of list comprehension lies in the hand of programmer or coder in the way he or she can utilize. So enjoy the coding and try to reduce the effort of typing using list comprehensions.

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Sunday, March 8, 2020

Is a Home Tutor Needed For Your Child


The demand for a qualified home tutor is increasing day by day. It is the best

option to take up home tuition as part-time jobs for earning. With the rising training, the many expert home tutor has become a favorite for parents and students. And those expert tutors are highly demanded in the market. 

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Saturday, March 7, 2020

Where Do I Find a Home Tutor Near Me?


I want to find a home tutor near me. This sounds easy enough, I think, but what I've found is that it's a lot more difficult than I had imagined. The information I've gathered tells me that in order to be able to get someone who will actually do the work for you, you really need to be looking for a tutor that is in your area. This means that you need to be looking for someone that lives in your town. This could take a lot of looking and could end up costing you quite a bit of money. I can't tell you how much I spent on people who claimed they lived in my area but when you add it all up, it's quite a bit.


Where Do I Find a Home Tutor Near Me? 


I want to find a home tutor near me. This sounds easy enough, I think, but what I've found is that it's a lot more difficult than I had imagined. The information I've gathered tells me that in order to be
able to get someone who will actually do the work for you, you really need to be looking for a tutor that is in your area. This means that you need to be looking for someone that lives in your town. This could take a lot of looking and could end up costing you quite a bit of money. I can't tell you how much I spent on people who claimed they lived in my area but when you add it all up, it's quite a bit. } The other option is to find a tutor who lives outside of your area. But, this is also going to cost you a lot of money and it is likely that the person you are working with will not have the time to dedicate to your personal needs. How do you find a tutor that will take your personal needs into consideration? In order to find someone that you can trust and turn to when you need them, the best place to go is online. There are many sites that will provide you with personal tutors from just about anywhere in the world. Just remember that when you find a tutor, that you need to trust the tutor with your child. If you find someone that has had some problems in the past, I suggest that you don't take that risk. You need to keep your kid safe and your kid's safety should be your first priority. Finding a home tutor near me doesn't have to be difficult, but it does take a little bit of time and research.

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